This document is a working document prepared by NIOSH and/or ORAU Team for use in discussions with 

the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper 

documents are not final NIOSH or ABRWH (or their technical support and review contractors) positions 

unless specifically marked as such. This document may contain information protected by the Privacy 

Act. 

Response to items 8,9, and 11 

in March 8, 2013 document titled 

“NIOSH/ORAU Team actions from March 7, 2013 Fernald WG meeting” 

Robert Morris, Karen Kent, and Elizabeth Brackett 

March 25, 2013 

Related to Th in vivo 1978-1988: 

8.	 Since the in vivo data includes highly exposed individuals like chemical operators as well 

as lower exposed individuals like Security and laundry workers, describe how we will 

ensure that applying a coworker approach to highly exposed individuals will bound their 

intakes. 

SC&A response: Issue is the implementation of a one-size fits all bounding model for all 

Fernald workers, given the inability to identify who worked with thorium and in which 

plant on any given campaign vs. current model 

Application of the FMPC coworker model will be consistent with that of other coworker models. The 

coworker model will be used to reconstruct doses to workers who may have been exposed to thorium 

when no monitoring data exist, or when inadequate monitoring data are available (e.g., a result early in 

the employment period with no subsequent monitoring). The judgment concerning who may have been 

exposed is made by the dose reconstructor based on the period of employment, job description, work 

location, information supplied by the claimant, and other available information in the claimant file. The 

50th percentile value, with the associated GSD, of the coworker model will be applied in most cases. In 

the unusual cases in which a worker may have been highly exposed, for example a chemical operator or 

chemical group laborer, the 95th percentile value of the coworker distribution would be applied. For 

example, the 95th percentile coworker intakes would be applied for a chemical operator with no record 

of in vivo monitoring for thorium-related isotopes. 

Reference documents that explain which workers were subject to in vivo monitoring exist; for example, 

SRDB Reference ID# 2895, which was published in 1975 and Reference ID# 85067 which was published 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This document is a working document prepared by NIOSH and/or ORAU Team for use in discussions with 

the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper 

documents are not final NIOSH or ABRWH (or their technical support and review contractors) positions 

unless specifically marked as such. This document may contain information protected by the Privacy 

Act. 

in 1987. According to SRDB Reference ID# 85067, in 1987 the FMPC policy was to base the frequency of 

in vivo measurements on job classification and potential for internal exposure. Some workers were to be 

monitored annually due to high exposure potential. This includes Chemical Operators and Chemical 

Group Laborers. Workers with lower exposure potential, for example Mechanical Department Laborer 

or Machine Tool Operators, were monitored biennially. Less exposed workers were to be monitored on 

a once-every-four-years basis. Workers whose job classifications were not listed were not included in 

the routine in vivo monitoring program. Laundry workers were included in the monitored group every 

fourth year. Security personnel were not listed, and so they were not included in the routine in vivo 

monitoring program. 

Related to Th in vivo 1978-1988: 

9. Specify who the coworker model will be applied to. 

SC&A response: See response to #8 

See response to Item 8. 

Related to Th DWE intake method: 

11. Specify who the Th DWE exposures will be applied to. 

SC&A response: See response to #8 

See response to Item 8. Also note that the thorium DWE intake method is likely to be the only available 

source of thorium intake data during the period when it was used. As a result, this method will be 

applied to workers who have the exposure potential based on the criteria listed in the response to Item 

8.